Let yourself feel the feelings. Grieve, cry, be angry, whatever you need to do. If all you want to do is curl up on the couch and eat plain slices of bread for a week, do that. Take a little time off work if you can and want to.

If it's upsetting to see, get rid of the other person's stuff. If you're angry, print a few pictures of them to then tear up and burn. That kind of thing.

Don't do anything permanent, like throwing into the river their family heirloom that you found under the couch. Don't rip apart your bed because you both slept there (unless you can easily afford to replace it and will find this very satisfying). Don't lash out at them or their loved ones. But privately, feel it. Let it move through you. Be sad and sulky and prone to crying fits (when you're somewhere suitable) if that feels right. And when you start to feel a little better, start shifting your life back to normal. Daydream about what you want from life, maybe things you couldn't have before, and think about ways to get there.

And be gentle with yourself all the while. This is one of the hardest experiences most people will ever have. It's really, really hard.

Best wishes to you!